NSF PR 01-87 - October 30, 2001
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Biocapsule Can Provide Steady Insulin Supply; Potential
Breakthrough for Diabetes Patients
Pushing the frontiers of drug delivery technology,
a biomedical engineer at the University of Illinois
at Chicago has developed an implantable capsule that
releases a steady supply of insulin to the bloodstream
of people with diabetes.
The biocapsule, developed by Tejal Desai with support
from the National Science Foundation (NSF), features
two innovations designed to overcome previous obstacles.
A biological process allows the capsule to continuously
produce insulin, rather than using up a limited supply.
The capsule is made of a material designed to overcome
the problem of implant rejection.
"The capsule essentially acts as a bioreactor; it contains
insulin-secreting cells that borrow nutrients from
the body to keep producing insulin indefinitely,"
Desai said. "As long as the body produces glucose,
the cells will respond with insulin."
Desai has also broken new ground by developing a successfully
implantable micro-scale device. Tiny devices made
with microchip technology have been researched extensively
for implantable medical applications, but biocompatibility
has been a continuing problem.
To prevent the capsule from being attacked and destroyed
by the immune system, Desai developed a silicon membrane
covered with tiny uniform pores, each seven nanometers
across. The membrane acts as a "microfilter," allowing
the secretion of insulin from the capsule but blocking
the entrance of antibodies. The membrane is fabricated
with photolithographic techniques commonly used for
Desai reported the results of short-term testing of
the capsule, and the prospects for other micro-devices
for drug delivery, today at a meeting of the American
Vacuum Society in San Francisco, California. The results
will be published in the November issue of IEEE
Transactions in Biomedical Engineering.
The next steps are testing the capsule for long-term
usage and evaluating the ideal dosage level.